All conventional skateboards include four wheels; two wheels on the underside front portion of the board and two wheels on the underside rear portion. It has always been deemed necessary to provide the front and rear wheels in spaced pairs in order that the differential speed of the rollers on the inside of a turn as compared to the outside can be accommodated by the spaced pair of rollers.
The provision of front and rear pairs of rollers has required rather sophisticated mounting means in order to provide a skateboard capable of various maneuvers. Control of a skateboard is almost wholly determined by the distribution of weight on the board surface, the board being caused to turn by shifting the weight from one longitudinal edge of the board to the other. Tilting of the board in this manner is transmitted through the mounting means to the front and rear pairs of wheels to cause them to turn so that the board will thus follow in a curved path generally in the direction of the tilt. As presently constructed, the various supporting arrangements for the rollers or wheels includes some type of resilient means such as thick rubber washers which may be clamped down on the wheel supporting structure in such a manner as to bias the axis of the wheels into a parallel relationship with the bottom surface of the skateboard in which position the wheels are facing forwardly. Changes in the degree of biasing force is generally accomplished by simply tightening a screw.
While skateboards of the foregoing construction have been fairly successful, there are still many problems that arise. One of the major problems is that of proper traction between the wheels and a pavement or other surface on which the skateboard is travelling. Generally, the larger the engagement area of the wheel with the surface, the better is the traction and towards this end, it has become the practice to make the pairs of wheels as wide as possible. However, the width of the wheels is limited since it is undesirable to have the outer sides of the wheels overhang the edge of the skateboard. In such a situation, for example, severe tilting of the board can cause one of the longitudinal edges to engage the wheel and thus stop its rotation with disastrous results.
A second problem is that involved with the swivel mounting of the wheels and the resilient arrangement for returning them to a neutral position. As stated, this is generally accomplished by rubber washers or pads, but these elements can become worn and loose their resiliency. Further, the adjusting means in the form of a threaded screw is not always reliable as it can work loose.
Finally, in the construction of present day skateboards, the turning radius is limited as a consequence of the angulation of the swivelling axis which in most skateboards exceeds 50.degree.(90.degree.would constitute a vertical swivel axis).